(a) Permits. - Any airport zoning regulations adopted under this chapter may require that a permit be obtained before any new structure or use may be constructed or established and before any existing use or structure may be substantially changed or substantially altered. All such regulations may provide rules under which nonconforming uses shall be discontinued and removed in case of being abandoned, destroyed, deteriorated or decayed. In any event, however, all such regulations shall provide that before any nonconforming structure or tree may be replaced, substantially altered, rebuilt, allowed to grow higher or replanted, a permit must be secured from the administrative agency authorized to administer and enforce the regulations, authorizing such replacement or change; but no such permit shall be required to make maintenance repairs to or to replace parts of existing structures which do not enlarge or increase the height of an existing structure. No permit shall be granted that would allow the establishment or creation of an airport hazard or permit a nonconforming structure or tree or nonconforming use to be made or become higher or become a greater hazard to air navigation than it was when the applicable regulation was adopted or than it is when the application for a permit is made.

(b) Variances. - Any person desiring to erect any structure, or increase the height of any structure, or permit the growth of any tree, or otherwise use his property in violation of airport zoning regulations adopted under this chapter, may apply to the administrative agency for a variance from the zoning regulations in question. Such variances shall be allowed where a literal application or enforcement of the regulations would result in practical difficulty or unnecessary hardship and the relief granted would not be contrary to the public interest but do substantial justice and be in accordance with the spirit of the regulations and this chapter; provided, that any variance may be allowed subject to any reasonable conditions that the board of adjustment may deem necessary to effectuate the purposes of this chapter.

(c) Hazard marking and lighting. - In granting any permit or variance under this section, the administrative agency may, if it deems such action advisable to effectuate the purposes of this chapter and reasonable in the circumstances, so condition such permit or variance as to require the owner of the structure or tree in question to permit the political subdivision, at its own expense, to install, operate and maintain thereon such markers and lights as may be necessary to indicate to flyers the presence of an airport hazard, upon payment to the owner for all damage resulting to his property by such maintenance.